SARS-CoV-2, periodontal pathogens, and host factors: The trinity of oral post-acute sequelae of COVID-19.

COVID-19 as a pan-epidemic is waning but there it is imperative to understand virus interaction with oral tissues and oral inflammatory diseases. We review periodontal disease (PD), a common inflammatory oral disease, as a driver of COVID-19 and oral post-acute-sequelae conditions (PASC). Oral PASC identifies with PD, loss of teeth, dysgeusia, xerostomia, sialolitis-sialolith, and mucositis. We contend that PD-associated oral microbial dysbiosis involving higher burden of periodontopathic bacteria provide an optimal microenvironment for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. These pathogens interact with oral epithelial cells activate molecular or biochemical pathways that promote viral adherence, entry, and persistence in the oral cavity. A repertoire of diverse molecules identifies this relationship including lipids, carbohydrates and enzymes. The S protein of SARS-CoV-2 binds to the ACE2 receptor and is activated by protease activity of host furin or TRMPSS2 that cleave S protein subunits to promote viral entry. However, PD pathogens provide additional enzymatic assistance mimicking furin and augment SARS-CoV-2 adherence by inducing viral entry receptors ACE2/TRMPSS, which are poorly expressed on oral epithelial cells. We discuss the mechanisms involving periodontopathogens and host factors that facilitate SARS-CoV-2 infection and immune resistance resulting in incomplete clearance and risk for 'long-haul' oral health issues characterising PASC. Finally, we suggest potential diagnostic markers and treatment avenues to mitigate oral PASC.

Assessment of the Antibacterial Effect of Vitamin D3 against Red Complex Periodontal Pathogens: A Microbiological Assay.

AIM: The study aims is to evaluate the antibacterial effect of vitamin D3 against the red complex bacteria, Porphyromonas gingivalis, Treponema denticola, Tannerella forsythia in chronic periodontitis patients. MATERIALS AND METHODS: The study comprised 98 participants with chronic periodontitis. All clinical parameters including plaque index (PI), gingival bleeding index (GBI), probing pocket depth (PPD), clinical attachment level (CAL), and a microbiological assay of P. gingivalis, T. denticola, T. forsythia were assessed at the baseline. All study participants who underwent scaling and root planning were divided into two groups, A and B, each with 49 patients and only group B patients were advised to take vitamin D supplementation of 60,000 IU granules, once daily for 2 months. All the patients of both the groups were recalled at the end of 2nd month and all the clinical and microbiological parameters were reassessed. RESULTS: After two months, there was a reduction in all the clinical markers in both groups, but the group B patients showed more improvement following non-surgical treatment vitamin D intake. There was also a statistical reduction in P. gingivalis, T. denticola, and T. forsythia following administration of vitamin D in group B patients compared to group A. CONCLUSION: These discoveries proposed that vitamin D has a superb antimicrobial impact against red complex periodontal microbes and might be considered a promising compound in the counteraction of periodontal disease. CLINICAL SIGNIFICANCE: Vitamin D is considered to possess anti-inflammatory and antimicrobial activity, which may help to delay the progression of periodontitis. So, vitamin D3 can be used as a potential supplement that could be employed to stop the advancement of periodontal disease. How to cite this article: Govindharajulu R, Syed NK, Sukumaran B, et al. Assessment of the Antibacterial Effect of Vitamin D3 against Red Complex Periodontal Pathogens: A Microbiological Assay. J Contemp Dent Pract 2024;25(2):114-117.

Designing Novel Multi-Epitope Vaccine Construct against Prevotella intermedia-Interpain A: An Immunoinformatics Approach.

Background and Objectives: Periodontitis is a chronic multifactorial inflammatory infectious disease marked by continuous degradation of teeth and surrounding parts. One of the most important periodontal pathogens is P. intermedia, and with its interpain A proteinase, it leads to an increase in lethal infection. Materials and Methods: The current study was designed to create a multi-epitope vaccine using an immunoinformatics method that targets the interpain A of P. intermedia. For the development of vaccines, P. intermedia peptides InpA were found appropriate. To create a multi-epitope vaccination design, interpain A, B, and T-cell epitopes were found and assessed depending on the essential variables. The vaccine construct was evaluated based on its stability, antigenicity, and allergenicity. Results: The vaccine construct reached a more significant population and was able to bind to both the binding epitopes of major histocompatibility complex (MHC)-I and MHC-II. Through the C3 receptor complex route, P. intermedia InpA promotes an immunological subunit. Utilizing InpA-C3 and vaccination epitopes as the receptor and ligand, the molecular docking and dynamics were performed using the ClusPro 2.0 server. Conclusion: The developed vaccine had shown good antigenicity, solubility, and stability. Molecular docking indicated the vaccine's 3D structure interacts strongly with the complement C3. The current study describes the design for vaccine, and steady interaction with the C3 immunological receptor to induce a good memory and an adaptive immune response against Interpain A of P. intermedia.

Effects of Probiotics Mouthwash on Levels of Red Complex Bacteria in Chronic Periodontitis Patients: A Clinico-microbiological Study.

AIM: The red complex includes Porphyromonas gingivalis, Treponema denticola, and Tannerella forsythia, which are recognized as the most important pathogens and are the indicators of infection in chronic periodontal disease. This study was to assess the levels of red complex bacteria in chronic periodontitis patients following treatment with probiotic mouthwash. MATERIALS AND METHODS: Twenty chronic periodontitis patients with ages ranging from 18 to 55 years were recruited for the study. The control group was given placebo mouthwash and the study group was given probiotic mouthwash. After clinical monitoring and scaling and root planing, the collected plaque samples at baseline and 14th day were transferred for microbiological analysis by transport media for Conventional Multiplex Polymerase Chain Reaction. RESULTS: On the 14th day, all the clinical parameters were significantly reduced in the study group with gingival index (p = 0.003 HS) and plaque index (p = 0.001 VHS). In the study group, there was significant bacterial cell reduction with T. denticola (p = 0.041 S) and T. forsythia (p = 0.037 S). CONCLUSION: In patients with chronic periodontitis, treatment with probiotic mouthwash significantly reduces the levels of red complex bacteria. CLINICAL SIGNIFICANCE: The use of probiotic mouthwash could be a useful adjunct to scaling and root planing in chronic periodontitis.

Evaluation of Reactive Oxygen Metabolites, Resistin, and Red Complex Bacteria in Obese Subjects with or without Periodontitis.

AIM: The study's aim was to assess and compare the clinical parameters, plasma reactive oxygen metabolites (ROM) levels, gingival crevicular fluid (GCF) resistin, serum resistin values, and red complex bacteria in obese or overweight subjects with and without periodontitis and also to determine the effect of non-surgical periodontal therapy (NSPT) on plasma ROM, serum, and GCF resistin values in obese or overweight subjects with chronic periodontitis. MATERIAL AND METHODS: A total of 160 subjects were recruited and designated into four groups with 40 subjects each as group I - obese with chronic periodontitis; group II - normal weight subjects with chronic periodontitis; group III - obese subjects with healthy periodontium; and group IV - normal weight subjects with healthy periodontium. The periodontal parameters, plasma ROM, GCF resistin and serum resistin, and red complex bacteria levels were estimated at baseline. After baseline assessment, scaling and root planing (SRP) were done in the patients of groups I and II. Two months after the completion of SRP, clinical parameters such as plaque index (PI), probing pocket depth (PPD), gingival index (GI), and clinical attachment loss (CAL), plasma ROM levels, serum resistin, and GCF resistin levels were analyzed. RESULTS: An increase in plasma ROM, GCF resistin, and red complex bacteria levels was observed in obese subjects with periodontal disease and the increase was noted in obese subjects with healthy periodontium. Comparing plasma ROM, GCF resistin values between groups I and II, 2 months after SRP, a decrease in these levels were observed in group II. CONCLUSION: Our study results depict that obesity can be considered as a risk indicator for periodontal disease. CLINICAL SIGNIFICANCE: Obesity has a negative impact on both general health and oral health. Promoting appropriate physical activity, healthy eating behavior, and oral hygiene practice are fundamental elements of the prevention of both obesity and periodontal disease.

Bacteria and oral cavity: a new story to tell.

Periodontal diseases include a mild and reversible form named gingivitis (GI), and periodontitis (PD) that is the main cause of tooth loss in adults. GI, that affects gums and coronal junctional epithelium, as well as periodontitis, that is characterized by loss of connective tissue attachment, are caused by a persistent inflammatory response promoted by alteration of periodontal biofilm. The aim of the study was to test whether the prevalence of each species was associated with a particular clinical condition. Periodontal evaluation of 756 unrelated patients was performed by the Periodontal Screening and Recording (PSR) system. Subgingival samples were obtained from the site with the worst PSR score. A selection of eleven bacterial species was evaluated by quantitative real time PCR. Quantitative and qualitative analyses help to better understand the microbial changes associated with different stages of periodontal disease.

Inhibitory Effect of Nepeta deflersiana on Climax Bacterial Community Isolated from the Oral Plaque of Patients with Periodontal Disease.

BACKGROUND: The red-complex bacteria are one of the most significant complexes found simultaneously in subgingival plaque next to the periodontal pocket. The current antibacterial treatment is not adequate, and multidrug resistance to it is developing. Henceforth, the antibacterial effect of the ethanolic extract of Nepeta deflersiana was put to test against red-complex bacteria in patients with chronic periodontitis. METHODS: Well diffusion and micro broth dilution procedure by Alamar blue were applied to assess the zone of inhibition (ZOI), the minimum inhibitory concentration (MIC), and the minimum bactericidal concentration (MBC). Anti-virulence efficacies of the plant extract that comprise of adherence and formation of biofilms were examined by the process of adherence and biofilm production assay. RESULTS: The crude extract of Nepeta deflersiana exhibited significant inhibitory outcome against periodontopathic bacteria with noteworthy MIC (0.78-3.12 mg/mL), inhibitory zone (12-20 mm), as well as MBC (3.12-12.50 mg/mL). The N. deflersiana extract inhibited bacterial adhesion ranging from 41% to 52%, 53% to 66%, and 60% to 79% at the given MIC × 0.5, MIC × 1, and MIC × 2 in succession. Substantial suppression was also developed in the biofilm production of the investigated periodontopathic strains following exposure to numerous concentrations of N. deflersianan extract for a period of 24 and 48 h. CONCLUSION: These outcomes divulge a new concept that N. deflersiana extract can be utilized to manufacture valuable antibacterial compounds to treat chronic and acute periodontitis. This identifies N. deflersiana as an essential natural source for future drug development.

Efficacy of (-)-epigallocatechin gallate delivered by a new-type scaler tip during scaling and root planing on chronic periodontitis: a split-mouth, randomized clinical trial.

BACKGROUND: (-)-Epigallocatechin Gallate (EGCG) as green tea catechins possessed antibacterial and anti-inflammatory effects on periodontal disease. This study was designed to evaluate the clinical and microbiological efficacy of scaling and root planing (SRP) using EGCG aqueous solution as coolants through a new-type ultrasonic scaler tip on chronic periodontitis. METHODS: This split-mouth, randomized clinical trial included 20 patients (2 drop-outs) with chronic periodontitis and the maxillary contra-lateral sides were allocated into test and control groups randomly. Through the new-type scaler tip, 762 sites with probing depth (PD) ≥ 4 mm were treated by SRP using EGCG solution or distilled water as coolants respectively. Clinical parameters and red complex pathogens in subgingival microbiome were evaluated at baseline, 3 and 6 months after treatments. RESULTS: During 6 months, the SRP plus EGCG medication contributed to additional PD reduction as 0.33 mm and gain of clinical attachment level as 0.3 mm compared with SRP alone, and approximate 8% more sites obtained PD reduction ≥ 2 mm (p < 0.05). Meanwhile, the mean relative abundance of Tannerella forsythia was significantly lower in the combined treatment group (p < 0.05). CONCLUSION: The purified EGCG showed the potential to improve the outcome of periodontal non-surgical treatment and the new-type scaler tip provided an alternative vehicle for subgingival medication. Trial registration The trial was registered in Chinese Clinical Trial Registry on 15 February 2020 (No.: ChiCTR2000029831, retrospectively registered). http://www.chictr.org.cn/showprojen.aspx?proj=49441 .

Effect of Ligilactobacillus salivarius and Other Natural Components against Anaerobic Periodontal Bacteria.

In this present study, the bacteriostatic effect of Salistat SGL03 and the Lactobacillus salivarius strain contained in it was investigated in adults in in vivo and in vitro tests on selected red complex bacteria living in the subgingival plaque, inducing a disease called periodontitis, i.e., chronic periodontitis. Untreated periodontitis can lead to the destruction of the gums, root cementum, periodontium, and alveolar bone. Anaerobic bacteria, called periopathogens or periodontopathogens, play a key role in the etiopathogenesis of periodontitis. The most important periopathogens of the oral microbiota are: Porphyromonas gingivalis, Tannerella forsythia, Treponema denticola and others. Our hypothesis was verified by taking swabs of scrapings from the surface of the teeth of female hygienists (volunteers) on full and selective growth media for L. salivarius. The sizes of the zones of growth inhibition of periopathogens on the media were measured before (in vitro) and after consumption (in vivo) of Salistat SGL03, based on the disk diffusion method, which is one of the methods of testing antibiotic resistance and drug susceptibility of pathogenic microorganisms. Additionally, each of the periopathogens analyzed by the reduction inoculation method, was treated with L. salivarius contained in the SGL03 preparation and incubated together in Petri dishes. The bacteriostatic activity of SGL03 preparation in selected periopathogens was also analyzed using the minimum inhibition concentration (MIC) and minimum bactericidal concentration (MBC) tests. The obtained results suggest the possibility of using the Salistat SGL03 dietary supplement in the prophylaxis and support of the treatment of periodontitis-already treated as a civilization disease.

Evaluation of antibacterial properties of Matricaria aurea on clinical isolates of periodontitis patients with special reference to red complex bacteria.

BACKGROUND: Chronic periodontitis has an interplay between different species of bacteria found in dental biofilms act a crucial role in pathogenesis and disease progression. The existing antibacterial therapy is inadequate, associated with many side effects as well as evolving multidrug resistance. Hence, novel drugs development with minimum or no toxicity is an immediate priority. METHODS: Antibacterial efficacy of ethanolic extract of Matricaria aurea was tested against clinical isolates, ie. Treponema denticol, Tannerella forsythia, Aggregatibacter actinomycetemcomitans and Porphyromonas gingivalis from the patients with chronic periodontitis. Zone of inhibition, the minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC) were investigated by well diffusion method and micro broth dilution assay using alamar blue. Anti-virulence properties of the extract, which include adherence property and the biofilm formation, were investigated by adherence as well as biofilm formation assay. RESULTS: Matricaria aurea extract showed potent inhibitory effect against pathogenic periodontal bacteria with the significant inhibitory zone (13-23 mm), MIC (0.39-1.56 mg/ml) as well as MBC (1.56-6.25 mg/ml). The M. aurea extract was able to inhibit bacterial adhesion ranged from 30 to 45%, 35 to 63% and 55 to 80% of MIC at MIC × 0.5, MIC × 1 and MIC × 2 respectively. Significant inhibition was found in biofilm formation to all the tested periodontal bacterial strains after the treatment with various concentrations of M. aurea extract for 24 and 48hrs. CONCLUSION: These results reveal for the first time that the Matricaria aurea extract might be the source of various compounds to be applied for chronic periodontitis therapy, which might draw these valuable compounds to the subsequent phase of development of the drug.

Microbiological dynamics of red complex bacteria following full-mouth air polishing in periodontally healthy subjects-a randomized clinical pilot study.

OBJECTIVES: Suppression of periodontal pathogens in the oral cavity of periodontally healthy individuals may lower the risk for periodontal or periimplant diseases. Therefore, the present study aimed to analyze the effect of supragingival debridement (SD) with adjunctive full mouth glycine powder air polishing (FM-GPAP) on the prevalence of periodontal pathogens in periodontally healthy individuals. MATERIALS AND METHODS: Eighty-seven systemically and periodontally healthy intraoral carriers of red complex bacteria, i.e., Porphyromonas gingivalis, Tannerella forsythia, and Treponema denticola or other periodontal pathogens including Aggregatibacter actinomycetemcomitans, Prevotella intermedia, and Eikenella corrodens were enrolled into the study and randomly assigned to receive SD with adjunctive FM-GPAP (test, n = 42) or SD alone (control, n = 45). In the first observation period, microbiological samples were obtained prior to, and 2, 5, and 9 days following intervention. If one of these periodontal pathogens could still not be identified, additional microbial sampling was performed after 6 and 12 weeks. RESULTS: The prevalence of red complex bacteria was significantly reduced in the test compared to the control group following treatment (p = 0.004) and at day 9 (p = 0.031). Intragroup comparison showed a significant (test, p < 0.001; control, p ≤ 0.01) reduction in the mean prevalence in both groups from BL through day 9 with an additional significant intergroup difference (p = 0.048) at day 9. However, the initial strong reduction returned to baseline values after 6 and 12 weeks. CONCLUSION: In periodontally healthy carriers of periodontal pathogens, FM-GPAP as an adjunct to SD transiently enhances the suppression of red complex bacteria. CLINICAL RELEVANCE: Whether the enhanced suppression of red complex bacteria by adjunctive FM-GPAP prevents the development of periodontitis in periodontally healthy carriers requires further investigations.

Comparative Evaluation of Two Different One-stage Full-mouth Disinfection Protocols using BANA Assay: A Randomized Clinical Study.

AIM: The aim of this study was to evaluate and compare two different one-stage full-mouth disinfection protocols in the treatment of chronic periodontitis by assessing dental plaque and tongue coat using BANA assay. MATERIALS AND METHODS: The present study was a prospective randomized clinical parallel arm study design including 40 healthy subjects randomly allocated into two groups, i.e., group A (Quirynen's protocol of one-stage full-mouth disinfection) and group B (Bollen's protocol of one-stage full-mouth disinfection). Subjects were assessed at baseline and six weeks using plaque index, gingival index, and sulcus bleeding index. Probing depth and relative clinical attachment level were also recorded at six weeks. Winkel tongue coat index and BANA were recorded at 8 weeks using subgingival plaque and tongue coat sample. RESULTS: Both group A and group B demonstrated statistically significant reduction in plaque index, gingival index, sulcus bleeding index, Winkel tongue coat index, reduction in probing depth, and gain in relative clinical attachment level on intragroup comparison. There was no significant difference in BANA assay score of subgingival plaque and tongue coat samples in between group A and group B. CONCLUSION: From the findings of this study, both Quirynen's protocol and Bollen's protocol of one-stage full-mouth disinfection are effective in plaque reduction and tongue coat reduction and achieve comparable clinical healing outcomes. CLINICAL SIGNIFICANCE: The difference in duration and mode of use of chlorhexidine as a chemical plaque control agent in the two treatment interventions of Quirynen's and Bollen's protocol of one-stage full-mouth disinfection did not demonstrate statistical significance in reducing sulcus bleeding index scores, reducing probing depths, and gain in relative clinical attachment levels.

Quantitative analysis of classical and new putative periodontal pathogens in subgingival biofilm: a case-control study.

BACKGROUND AND OBJECTIVES: A number of species/phylotypes have been newly implicated as putative periopathogens. The objective of this study was to explore associations among classical and new pathogens in subgingival biofilm and to assess their relative importance to chronic periodontitis. MATERIAL AND METHODS: Pooled subgingival biofilm samples were obtained from 40 patients with chronic periodontitis and 40 healthy controls. Taqman q-PCR assays were used to determine the absolute and relative counts of Porphyromonas gingivalis, Tannerella forsythia, Treponema denticola, Parvimonas micra, Filifactor alocis, oral Synergistetes and oral TM7s. Microbial associations were assessed using cluster analysis. Different statistical models were used to explore associations between microbial parameters and periodontitis. RESULTS: The median log and relative counts were lowest for TM7s (4.4 and 0.0016%, respectively) and highest for oral Synergistetes (7.2 and 1.4%, respectively). Oral Synergistetes clustered strongly with the red complex, particularly T. forsythia (100% rescaled similarity). All species/phylotypes except TM7s were significantly associated with periodontitis (Mann-Whitney test; p ≤ 0.005). However, P. gingivalis and F. alocis lost association after adjusting for confounders (ordinal regression). In receiving operator characteristic curve analysis, the log counts of oral Synergistetes were the best markers of periodontitis (82.5% sensitivity and specificity), followed by those of T. forsythia, P. micra and T. denticola. In prediction analysis, however, P. micra was the only microbial predictor of periodontal parameters. CONCLUSIONS: Oral Synergistetes are presented here as new members of the red complex, with relative importance to periodontitis exceeding that of the classical members. P. micra is shown as an important periodontal pathogen warranting more attention.

The novel association between red complex of oral microbe and body mass index in healthy Japanese: a population based cross-sectional study.

Microbiota has been thought to be one of important environmental factors for obesity or Type 2 diabetes mellitus. Among oral microbe, Porphyromonas gingivalis, Treponema denticola and Tannellera forsythia are known as risk factors, so called red complex, for periodontitis. Red complex could also be a risk factor for obesity. However, recent study indicated that obesity was not improved by periodontal therapy. Thus, we performed a cross sectional study to reveal the association of oral microbe with body mass index in a healthy population. Healthy individuals were randomly recruited. The infections of oral microbe were identified by Taqman polymerase chain reaction. The relationships between number of red complex and body mass index or waist circumference were analyzed. Two hundred and twenty-two apparently healthy Japanese were enrolled. BMI and waist circumference as well as age, periodontitis, number of brushing teeth were significantly associated with the number of red complex after adjusting covariance. The effect size of body mass index or waist circumference was 0.023 (p = 0.028) or 0.024 (p = 0.024), respectively. Body mass index and waist circumference were independently associated with the number of red complex among apparently healthy Japanese. The current observation implies the possibility that oral microbe was associated with obesity in healthy population.

Evaluation of Antimicrobial Susceptibility and Resistance Patterns of Treponema denticola Isolated From Periodontal Disease: An In Vitro Study.

Background Periodontal disease poses a significant oral health challenge, involving inflammatory conditions impacting tooth-supporting structures. Treponema denticola, a "red complex" organism, plays a crucial role in periodontal pathogenesis, forming biofilms in subgingival environments and contributing to dysbiosis. Antimicrobial therapy is pivotal in managing periodontal disease, requiring a nuanced understanding of susceptibility patterns exhibited by key pathogens like T. denticola. Aims and objectives This study aims to investigate the antimicrobial susceptibility and resistance profiles of Treponema denticola, a prominent bacterium in periodontal disease, by examining its responses to various antimicrobial agents commonly used in periodontal therapy. Methodology Plaque samples were meticulously collected from individuals diagnosed with periodontal disease to ensure a diverse representation of the oral microbiome. All the samples were cultured, and red complex bacteria were isolated under anaerobic culture. Treponema denticola isolates were cultured from these samples under anaerobic conditions, and molecular techniques were employed for species identification. A comprehensive panel of antimicrobial agents was selected to assess the response of Treponema denticola. In vitro antimicrobial susceptibility testing (AST) was conducted using the antimicrobial gradient method, employing a hybrid approach combining elements of disk-diffusion and dilution methods. Results Treponema denticola had exhibited resistance to metronidazole, a commonly used antibiotic effective against anaerobic bacteria, emphasizing limitations in its applicability. However, the bacterium displayed sensitivity to tetracycline, imipenem, cefoperazone, chloramphenicol, clindamycin, and moxifloxacin, offering diverse therapeutic options. The antimicrobial gradient strip test provided detailed minimum inhibitory concentration (MIC) values, contributing to a nuanced understanding of susceptibility and resistance patterns. Conclusion This study significantly advances our understanding of Treponema denticola's antimicrobial susceptibility and resistance profiles in the context of periodontal disease. The findings underscore the importance of tailored treatment strategies and contribute to broader efforts in antimicrobial stewardship, aligning with global initiatives to combat antibiotic resistance. This research lays the foundation for more effective and personalized approaches to periodontal care, emphasizing the intricate microbial dynamics associated with periodontal health and disease.

Association of Periodontal Red Complex Bacteria With the Incidence of Gastrointestinal Cancers: A Systematic Review and Meta-Analysis.

Porphyromonas gingivalis is the primary microbe in the "periodontal red complex" bacteria (PRCB) along with Tannerella forsythia and Treponema denticola, which are linked to periodontal disease (PD). These pathogens are also implicated in various systemic disorders, but their association with the incidence of gastrointestinal (GI) cancer is less explored. A systematic review followed by a meta-analysis was conducted as per standard guidelines (Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) 2022) to find this association between GI cancers and PRCB after a literature search for full-text papers in the English language (between 2010 and 2023) in databases (Cochrane Library, PubMed, and Web of Science) with suitable keywords using the Boolean search strategy. Data extraction involved titles, abstracts, and full texts retrieved and scored by the modified Newcastle-Ottawa Scale. The data were analyzed by the Review Manager (RevMan 5.2, Cochrane Collaboration, Denmark). Standard Cochran Q test and I2 statistics (for heterogeneity) and a random effects model (pooled OR with 95% CI) were applied to report results. P. gingivalis among the PRCB was linked to GI cancers (OR: 2.16; 95% CI: 1.34-3.47). T. forsythia and T. denticola did not show meaningful associations as per existing evidence for GI cancers.

Investigating the role of a Tannerella forsythia HtrA protease in host protein degradation and inflammatory response.

Introduction: Degradation of host proteins by bacterial proteases leads to the subversion of the host response and disruption of oral epithelial integrity, which is considered an essential factor in the progression of periodontitis. High-temperature requirement A (HtrA) protease, which is critical for bacterial survival and environmental adaptation, is found in several oral bacteria, including the periodontal pathogen Tannerella forsythia. This study investigated the proteolytic activity of HtrA from T. forsythia and its ability to modulate the host response. Methods: HtrA of T. forsythia was identified bioinformatically and produced as a recombinant protein. T. forsythia mutants with depleted and restored HtrA production were constructed. The effect of T. forsythia wild-type, mutants and recombinant HtrA on the degradation of casein and E-cadherin was tested in vitro. Additionally, the responses of human gingival fibroblasts and U937 macrophages to the different HtrA-stimuli were investigated and compared to those triggered by the HtrA-deficient mutant. Results: T. forsythia wild-type producing HtrA as well as the recombinant enzyme exhibited proteolytic activity towards casein and E-cadherin. No cytotoxic effect of either the wild-type, T. forsythia mutants or rHtrA on the viability of host cells was found. In hGFB and U937 macrophages, both T. forsythia species induced an inflammatory response of similar magnitude, as indicated by gene and protein expression of interleukin (IL)-1ß, IL-6, IL-8, tumour necrosis factor α and monocyte chemoattractant protein (MCP)-1. Recombinant HtrA had no significant effect on the inflammatory response in hGFBs, whereas in U937 macrophages, it induced a transient inflammatory response at the early stage of infection. Conclusion: HtrA of T. forsythia exhibit proteolytic activity towards the host adhesion molecule E-cadherin and has the potential to influence the host response. Its role in the progression of periodontitis needs further clarification.

Bacterial Periodontitis in Horses: An Epidemiological Study in Southern Italy.

Equine periodontal disease (EPD) is a painful oral inflammatory syndrome characterized by multifactorial pathogenesis. Although it is well known that bacterial proliferation and consequent gingivitis are caused by the decomposition process of food residues, in hypsodont species, the pathogenetic role and the different bacterial species involved in the progression of EPD must be fully clarified. This study aimed to investigate the association of bacteria, including the complex red bacteria (RCB), with EPD, and to evaluate possible EPD risk factors. Bacterial species, including Treponema denticola, Tannerella forsythia, Porphyromonas gingivalis (belonging to the RCB), Fusobacterium nucleatum, Veilonella parvula, and Prevotella intermedia, were investigated in 125 oral swabs from healthy and EPD-affected horses using real-time multiplex PCR. Subsequently, possible risk factors (i.e., age, gender, and breed of the animals and type of feed used) were evaluated using univariate and multivariate analyses. Tannerella spp. and Treponema spp. were detected in a significantly higher proportion of horses affected by EPD than in healthy animals, although pathogens belonging to RCB were detected in low number of horses. At the same time, none of the investigated pathogens was significantly associated with a particular stage of disease severity. Horses aged older than 20 years were at higher risk of EPD. The high rate of coinfection, statistically associated with EPD, supports the hypothesis that EPD is a complex syndrome characterized by the possible simultaneous involvement of several pathogens and an increased risk depending on the animal's age. Constant oral hygiene is the best prevention to prevent and treat the disease, especially in old animals.

A GntR family transcription factor in Porphyromonas gingivalis regulates bacterial growth, acylpeptidyl oligopeptidase, and gingipains activity.

Porphyromonas gingivalis is a keystone pathogen for periodontitis. The function of the GntR family transcription factor is poorly studied in P. gingivalis. Numerous processes govern bacterial growth. The survival and pathogenicity of P. gingivalis depend heavily on its capacity to acquire amino acids as nutritional sources. In this investigation, a GntR transcription factor, pg1007, was identified in P. gingivalis, the deletion of which significantly inhibited bacterial growth. The mutant strain also exhibited an increased extracellular activity of gingipains and acylpeptidyl oligopeptidase (AOP). Global gene expression profiling revealed that the expression levels of 59 genes were significantly altered in the Δpg1007 mutant, with an upregulation in gene expression for AOP, ABC transporters, and some membrane proteins. In addition, His-PG1007 protein was purified as a recombinant protein from Escherichia coli, and the conserved DNA sequence bound by it was determined using electrophoretic mobility shift assays and DNase I footprinting assays. Consequently, this study demonstrated that pg1007 is a crucial transcription factor in P. gingivalis and regulates the bacterial growth and activity of gingipains and AOP. These findings may enhance our understanding of the regulation of bacterial proliferation and protease activity in P. gingivalis.

CRISPR-Cas-Based Adaptive Immunity Mediates Phage Resistance in Periodontal Red Complex Pathogens.

Periodontal diseases are polymicrobial immune-inflammatory diseases that can severely destroy tooth-supporting structures. The critical bacteria responsible for this destruction include red complex bacteria such as Porphoromonas gingivalis, Tanerella forsythia and Treponema denticola. These organisms have developed adaptive immune mechanisms against bacteriophages/viruses, plasmids and transposons through clustered regularly interspaced short palindromic repeats (CRISPR) and their associated proteins (Cas). The CRISPR-Cas system contributes to adaptive immunity, and this acquired genetic immune system of bacteria may contribute to moderating the microbiome of chronic periodontitis. The current research examined the role of the CRISPR-Cas system of red complex bacteria in the dysbiosis of oral bacteriophages in periodontitis. Whole-genome sequences of red complex bacteria were obtained and investigated for CRISPR using the CRISPR identification tool. Repeated spacer sequences were analyzed for homologous sequences in the bacteriophage genome and viromes using BLAST algorithms. The results of the BLAST spacer analysis for T. denticola spacers had a 100% score (e value with a bacillus phage), and the results for T. forsthyia and P. gingivalis had a 56% score with a pectophage and cellulophage (e value: 0.21), respectively. The machine learning model of the identified red complex CRISPR sequences predicts with area an under the curve (AUC) accuracy of 100 percent, indicating phage inhibition. These results infer that red complex bacteria could significantly inhibit viruses and phages with CRISPR immune sequences. Therefore, the role of viruses and bacteriophages in modulating sub-gingival bacterial growth in periodontitis is limited or questionable.